Exploring new tools to add to my toolbox

Beaglebone

My motivation to learn about the BeagleBone Blue came from my rover Sawppy driving by the BeagleBoard foundation booth at SCaLE 17x. While this board might not the best fit for a six wheel drive four wheel steering rocker bogie mars rover model, it has a great deal of potential for other projects.

But what motivated the BeagleBone Blue? When brainstorming about what I could do with something cool, it’s always instructive to learn a little bit about where it came from. A little research usually pays off because the better my idea aligns with its original intent, the better my chances are of a successful project.

I found that I could thank the Coordinated Robotics Lab at University of California, San Diego for this creation. As teaching tool for one of the courses at UCSD, they created the Robotics Cape add-on for a BeagleBone Black. It is filled with goodies useful for robot projects they could cover in class. More importantly, with quadrature input to go along with DC motor output and a 9-axis IMU on top of other sensors, this board is designed for robots that react to their environment. Not just simple automata that flail their limbs.

The signature robot chassis for this brain is the eduMIP. MIP stands for Mobile Inverted Pendulum and the “edu” prefix makes it clear it’s about teaching the principles behind such systems and invite exploration and experimentation. Not just a little self-balancing Segway-like toy, but one where we can dig into and modify its internals. I like where they are coming from.

BeagleBone Blue, then, is an offering to make robots like an eduMIP easier to build. By merging a BeagleBone Black with the Robotics Cape into a single board, removing components that aren’t as useful for a mobile robot (such as the Ethernet port) we arrive at a BeagleBone Blue.

Of course, the brawn of a robotics chassis isn’t much use without the smarts to make it all work together. Befitting university coursework nature and BeagleBoard Foundation’s standard procedure, its peripherals software now called Robot Control Library are documented and source code available on Github.

I could buy an eduMIP of my own to help me explore the BeagleBone Blue, and at $50 it is quite affordable. But I think I want to spend some time with the BeagleBone Blue itself before I spend more money.

Sawppy was a great ice breaker as I roamed through the expo hall of SCaLE 17x. It was certainly the right audience to appreciate such a project, even though there were few companies with products directly relevant to a hobbyist Mars rover. One notable exception, however is the BeagleBoard Foundation booth. As Sawppy drove by, the reception was: “Is that a Raspberry Pi? Yes it is. That should be a BeagleBone Blue!”

With this prompt, I looked into BBBlue in more detail. At $80 it is significantly more expensive than a bare Raspberry Pi, but it incorporates a lot of robotics-related features that a Pi would require several HATs to reach parity.

All BeagleBoards offer a few advantages over a Raspberry Pi, which the BBBlue inherits:

Integrated flash storage, Pi requires a separate microSD card.

Onboard LEDs for diagnosis information.

Onboard buttons for user interaction – including a power button! It’s always personally grated me a Raspberry Pi has no graceful shutdown button.

On top of that, BBBlue can also handle charging a 2S LiPo battery! Being able to leave the battery inside a robot would be a huge convenience. And people who don’t own smart battery chargers wouldn’t need to buy one if all they do is use their battery with a BBBlue.

8 PWM headers for RC-style servo motors.

4 H-bridge to control 4 DC motors.

4 Quadrature encoder inputs to know what those motors are up to.

9-axis IMU (XYZ accelaration + XYZ rotation)

Barometer

Sadly, a BBBlue is not a great fit for Sawppy because it uses serial bus servos making all the hardware control features (8 PWM header, 4 motor control, 4 quadrature input) redundant. But I can definitely think of a few projects that would make good use of a BeagleBone Blue. It is promising enough for me to order one to play with.